Re-entry catheters and related methods

ABSTRACT

Catheter devices and methods useable for directing a guidewire from a subintimal position within the wall of an artery into the true lumen of that artery or other applications wherein it is desired to direct a guidewire or other elongate device from one location to another location within a subject&#39;s body.

RELATED APPLICATIONS

This application is a Division of and claims the benefit of U.S. patentapplication Ser. No. 13/764,837 filed Feb. 12, 2013, now allowed. Thedisclosures of which are herein incorporated by reference in theirentirety.

FIELD OF THE INVENTION

The present invention relates generally to the fields of mechanicalengineering and medicine and more particularly to apparatus and methodsfor directing the advancement of catheters and other elongate medicaldevices.

BACKGROUND

There are numerous medical procedures in which it is desirable tore-direct a guidewire or other elongate medical device from one locationto another location within the body of a human or non-human animalsubject. For example, during endovascular treatment of total ornear-total occlusions in arteries, a guidewire may sometimes becomeembedded within the wall of an artery and it then becomes desirable tore-direct the distal end of that guidewire from its position within theartery wall into the true lumen of the artery.

Chronic total occlusions (CTOs) of arteries can occur in coronary aswell as peripheral arteries. It has been estimated that approximately10% of all endovascular angioplasty procedures are currently undertakento treat CTOs. The factor that is most determinative of whether a CTOcan be successfully treated by endovascular angioplasty is the ability(or inability) to initially pass a guidewire from a position within thetrue lumen of the artery proximal to the CTO, through or around the CTOand then into the true lumen of the artery at a location distal to theCTO. If a guidewire can be placed in this manner, it is typicallypossible to then perform angioplasty and stenting over that pre-placedguidewire to successfully restore blood flow through or around the CTO.

In CTOs where the occlusive matter is soft (or where the occlusion isless than total) a guidewire can simply be pushed through the occlusivematter itself, thereby achieving the desired placement of the guidewirewith the guidewire remaining within the true lumen of the artery.However, in other cases, such as where the artery is totally occluded byhard, calcified atherosclerotic plaque, the guidewire may tend todeviate to one side, causing the distal end of the guidewire topenetrate into the wall of the artery. When this occurs, the guidewiremay be pushed past the obstruction while still within the artery wall.This creates a “subintimal tract” within the wall. In many cases, theguidewire may be advanced sufficiently to extend the subintimal tractpast the obstruction. However, in these cases where the guidewire hasbeen successfully been advanced past the obstruction, the distal end ofthe guidewire typically remains entrapped within the newly-createdsubintimal tract. It then becomes necessary to re-direct the distal endof the guidewire from its entrapped location within the subintimal tractinto the true lumen of the artery at a location distal to theobstruction. Following successful re-entry of the guidewire into thetrue lumen, balloon dilation and stenting of the subintimal tract may beaccomplished to create a suitable channel for antegrade arterial bloodflow around the obstruction.

The prior art has included a number of true lumen re-entry devices thatare potentially useable to redirect a subintimally entrapped guidewireinto the true lumen of the artery. Commercial examples of such re-entrydevices include the Pioneer® Catheter (Medtronic Vascular, Santa Rosa,Calif.); the OUTBACK® LTD® Re-Entry Catheter (Cordis Corporation, Miami,Fla.) and the Enteer™ Re-entry System (Covidien/eV3, Plymouth, Minn.).Other examples are described in U.S. Pat. No. 5,830,222 (Makower); U.S.Pat. No. 6,068,638 (Makower); U.S. Pat. No. 6,159,225 (Makower); U.S.Pat. No. 6,190,353 (Makower, et al.); U.S. Pat. No. 6,283,951 (Flaherty,et al.); U.S. Pat. No. 6,375,615 (Flaherty, et al.); U.S. Pat. No.6,508,824 (Flaherty, et al.); U.S. Pat. No. 6,544,230 (Flaherty, etal.); U.S. Pat. No. 6,655,386 (Makower et al.); U.S. Pat. No. 6,579,311(Makower); U.S. Pat. No. 6,602,241 (Makower, et al.); U.S. Pat. No.6,655,386 (Makower, et al.); U.S. Pat. No. 6,660,024 (Flaherty, et al.);U.S. Pat. No. 6,685,648 (Flaherty, et al.); U.S. Pat. No. 6,709,444(Makower); U.S. Pat. No. 6,726,677 (Flaherty, et al.); U.S. Pat. No.6,746,464 (Makower); U.S. Pat. No. 8,323,261 (Kugler, et al.); U.S. Pat.No. 8,083,727 (Kugler, et al.); U.S. Pat. No. 7,938,819 (Kugler, etal.); U.S. Pat. No. 8,257,382 (Rottenberg, et al.); U.S. Pat. No.8,353,922 (Noriega, et al.); U.S. Pat. No. 8,043,314 (Noriega, et al.)

A recent published report describes the use of a balloon occlusiontechnique for diverting a guidewire from a subintimal tract into thetrue lumen of an artery, in lieu of using a re-entry catheter. In thisreported case, a 0.035 inch guidewire was initially used to form thesubintimal tract that extended past an obstructive lesion. That 0.035inch guidewire was then removed and a separate 0.018 inch guidewire wasselectively advanced into the subintimal tract. A low-profile ballooncatheter was then advanced over the 0.018 inch wire into the subintimaltract. The balloon was inflated to block the subintimal tract. A 0.035inch guidewire was then advanced through the subintimal tract next tothe balloon catheter. The presence of inflated balloon within thesubintimal tract caused the advancing 0.035 inch guidewire to divert outof the initial subintimal tract and into the true lumen of the artery,distal to the obstruction. Although this procedure did successfullycause the 0.035 inch guidewire to re-enter the true lumen of the arterywithout use of a separate re-entry catheter, this procedure did involveseveral time consuming steps and required the use of several guidewiresas well as a separate balloon catheter. Additionally, as the authorsnote, this procedure must be performed with caution as advancement ofthe 0.035 inch guidewire past the inflated balloon could result ininadvertent perforation of the artery with resultant hematoma orarteriovenous fistula formation. Jaffan A. A., et al., Balloon OcclusionOf Subintimal Tract To Assist Distal Luminal Reentry Into PoplitealArtery, J Vasc Interv Radiol. 2012 October; 23 (10): 1389-91.

There remains a need in the art for the development of different andimproved devices and methods useable for redirecting a subintimallyentrapped guidewire back into the true lumen of an artery in a safe andefficient manner.

SUMMARY OF THE INVENTION

The present invention provides catheter devices and methods useable fordirecting a guidewire from a subintimal position within the wall of anartery into the true lumen of that artery or other applications whereinit is desired to direct a guidewire or other elongate device from onelocation to another location within a subject's body.

In accordance with one aspect of the invention, there is provided aguidewire directing device (i.e., a true lumen re-entry device) thatcomprises an elongate shaft having a distal portion with a distal endand a lumen that extends to a distal outlet opening. An expandablemember (e.g., a balloon or expandable cage) is positioned on the distalportion of the elongate shaft. At least one navigation apparatus is alsopositioned on the distal portion of the elongate shaft. Proximal end(s)of the navigation apparatus is/are attached to the device shaft whiledistal end(s) of the navigation apparatus are unattached to the elongateshaft. The device is transitionable between a) a first configurationwherein the expandable member is non-expanded and the distal portion ofthe elongate shaft is substantially straight and b) a secondconfiguration wherein the expandable member is expanded, thereby causingthe expandable member to displace to one side of the navigationapparatus, which in turn results in lateral curvature of the distalportion of the elongate shaft. This device is advanceable, while in itsfirst configuration, over a guidewire whose distal end is subintimallyentrapped within an artery wall. With the guidewire retracted into thelumen of the device, the expandable member is expanded, causing thedevice to transition from its first configuration to its secondconfiguration while situated within the subintimal space. This causesthe expandable member to displace inwardly toward the true lumen ratherthan outwardly toward the muscular sheath of the artery, as this is thepath of least resistance to its expansion. As this occurs, the distalportion of the elongate shaft curves toward the true lumen of the arterysuch that the distal opening of the device lumen is aimed or directedtoward the artery's true lumen. The guidewire (or alternatively someother elongate device such as a probe, needle, stylet, penetrator, etc)is then advanced out of the distal opening of the device and into thetrue lumen of the artery. The device may then be returned to its firstconfiguration and removed from the body, leaving the guidewire in place.Other devices (e.g., balloon catheters, stents, etc.) may then bedelivered over the guidewire and used to establish a blood flow channelaround the arterial obstruction.

Further in accordance with the present invention there are providedmethods for causing a guidewire that has become entrapped in asubintimal tract within a blood vessel wall to re-enter the true lumenof the blood vessel without requiring the use of additionalguidewire(s).

Still further aspects, details and embodiments of the present inventionwill be understood by those of skill in the art upon reading thefollowing detailed description of the invention and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of one embodiment of a re-entry catheter of thepresent invention.

FIG. 1A is a top view of portion 1A of FIG. 1.

FIG. 1B is a side top view of portion 1A of FIG. 1.

FIG. 1C is a transverse sectional view through line 1C-1C of FIG. 1.

FIG. 1D is an end view of the device of FIG. 1.

FIG. 1E is a top view of a distal end portion of an alternativeconstruction of the device of FIG. 1.

FIG. 2 is a schematic diagram showing arteries of a human leg.

FIG. 3 is an anatomical diagram showing the histological layers of anartery.

FIG. 4A shows one step in a method for using the re-entry catheter ofFIG. 1 to perform a transluminal, catheter-based bypass of a CTO in anartery.

FIG. 4B shows another step in a method for using the re-entry catheterof FIG. 1 to perform a transluminal, catheter-based bypass of a CTO inan artery.

FIG. 4C shows another step in a method for using the re-entry catheterof FIG. 1 to perform a transluminal, catheter-based bypass of a CTO inan artery

FIG. 4D shows another step in a method for using the re-entry catheterof FIG. 1 to perform a transluminal, catheter-based bypass of a CTO inan artery.

FIG. 4E shows another step in a method for using the re-entry catheterof FIG. 1 to perform a transluminal, catheter-based bypass of a CTO inan artery.

FIG. 4F shows another step in a method for using the re-entry catheterof FIG. 1 to perform a transluminal, catheter-based bypass of a CTO inan artery.

FIG. 4G shows another step in a method for using the re-entry catheterof FIG. 1 to perform a transluminal, catheter-based bypass of a CTO inan artery.

FIG. 5 is a partial side view of another embodiment of a re-entrycatheter of the present invention in a first configuration.

FIG. 5A is a partial perspective view of the re-entry catheter of FIG. 5disposed in a second configuration.

FIG. 6 is a sectional, schematic diagram showing the re-entry catheterof FIG. 5 being used in a procedure to bypass a CTO in an artery.

FIG. 7 shows one embodiment of the navigation apparatus component of are-entry catheter of the present invention.

FIG. 7A is a perspective view of a navigation apparatus component ofFIG. 7 in an expanded configuration.

FIG. 7B is a side view of the distal portion of a re-entry catheterwhich incorporates the navigation apparatus component of FIG. 7, whiledisposed in a first configuration.

FIG. 7C is a perspective view showing the re-entry catheter of FIG. 7Bdisposed in a second configuration.

FIG. 7D is a perspective view showing the re-entry catheter of FIG. 7Bdisposed in a second configuration with a guidewire extending out of thedistal end of the catheter.

FIG. 8 shows another embodiment of a navigation apparatus component of are-entry catheter of the present invention.

FIG. 8A is a side view of the distal portion of a re-entry catheterwhich incorporates the navigation apparatus component of FIG. 8, whiledisposed in a first configuration.

FIG. 8B is a perspective view showing the re-entry catheter of FIG. 8Adisposed in a second configuration.

DETAILED DESCRIPTION

FIGS. 1 through 1E generally show one embodiment of a re-entry catheterdevice 10 of the present invention. This re-entry catheter device 10generally comprises a flexible elongate shaft 12, a navigation apparatus14 and balloon 16 positioned on a distal portion of the elongate shaft12 and a proximal hub 20 on the proximal end of the elongate shaft 12.Preferably, balloon 16 is a compliant balloon. A guidewire lumen 18extends through the elongate shaft 12 and terminates distally in anopening at the distal end DE of the shaft 12. A balloon inflation lumen26 also extends through the shaft 12 to facilitate inflation anddeflation of the balloon 16. The proximal hub 20 has a proximal port 24which communicates with the guidewire lumen 18 and a balloon inflationport 22 which communicates with the balloon inflation lumen 26.

In the particular embodiment of FIGS. 1 through 1E, the navigationapparatus 14 generally comprises a loop shaped (e.g., U shaped)structure which comprises a right side portion 14 a, a left side portion14 b and an open area 14 c. The proximal ends of the right and left sideportions 14 a, 14 b are separate and attached to opposite sides of theelongate shaft, proximal to balloon 16. The distal ends of the right andleft side portions 14 a, 14 b are conjoined or commonly connected to aunitary distal end member that forms the distal end of the navigationapparatus 14. The distal end of the navigation apparatus 14 is freefloating and unattached to the elongate shaft 12. A guidewire passageaperture 19 extends axially through the distal end of the navigationapparatus 14, as shown.

The navigation apparatus 14 may be formed of any suitable material(s)such as metal and/or plastic. In some embodiments, all of part of thenavigation apparatus 14 may be formed of superelastic nickel-titanium(i.e., Nitinol). In this regard, the navigation apparatus may be formedof wire or other elongate material (e.g., strips or ribbons). Or, insome embodiments, it may be cut from a nickel-titanium tube, as will bediscussed in more detail herebelow in relation to FIGS. 7 through 8B.

Also, the navigation apparatus 14 may be of one-piece constructionformed from a single component (e.g., a single wire, tube, ribbon, etc.)or it may be fabricated or constructed from more than one component. Oneexample of multiple component construction is shown in FIG. 1E, whereinthe navigation apparatus 14(alt) comprises right and left metal sideportions 14 a(alt), 14 b(alt) which are molded, fused or affixed to apolymer end member 15 having the guidewire passage aperture 19 formedtherein. This polymer end member 15 may be injection molded or otherwiseformed to any desired shape. For example, this end member 15 may have ablunt pointed tip designed to effect atraumatic blunt tissue separationas it advances through a subintimal tract within an artery wall.

The balloon 16 may be of any any suitable type or formed of any suitabletype of material. In the particular example shown in the drawings, theballoon 16 comprises a compliant balloon.

As shown in conjunction with the top view of FIG. 1A, a longitudinalaxis LA and a transverse axis TA are projectable through the navigationmember 14.

As seen in FIGS. 1A and 1B, when this device 10 is in its firstconfiguration, the balloon 16 is deflated and the distal portion of theelongate shaft 12 extends straight within the open area 14 c of thenavigation apparatus 14 such that the open distal end DE of the elongateshaft 12 is slightly proximal to, and may be aligned with, the guidewirepassage aperture 19 located in the distal end of the navigationapparatus 14. This allows the device 10 to be advanced over asubintimally entrapped guidewire. The guidewire passage aperture 19helps in stabilizing the navigation of apparatus 14. The navigationapparatus 14 is coupled to the guidewire by passage of the guidewirethrough aperture 19, thereby keeping the navigation apparatus 14substantially parallel to the guidewire and deterring inadvertentlateral movement of the navigation apparatus 14 as the device 10 isadvanced over the guidewire along the subintimal tract

When it is desired to transition the device 10 to its secondconfiguration, the balloon 16 is inflated. As the balloon 16 expands,its width becomes wider than the width of the open area 14 c within thenavigation apparatus 14. This causes the balloon to selectively bulgeeither above or below the open area 14 c. Typically, this selectivebulging of the balloon will be in whichever direction presents the leastresistance to its expansion. For example, if body tissue locatedimmediately below the open area 14 c is less elastic or lesscompressible than body tissue located immediately above the open area 14c, the balloon 16 will selectively bulge below the open area 14 c. Thiscauses concurrent curvature of the distal portion of the elongate shaft12 in the same direction.

To appreciate the advantageous uses of the above-described re-entrycatheter device 10, it is helpful to understand the disorders it isuseable to treat. In many cases, the device 10 may be used to treat aCTO in an artery of the leg which has resulted from uncontrolledPeripheral Arterial Disease (PAD). PAD in a lower limb can causecramping, intermittent claudication and numbness in the affected leg,especially while walking or during exertion. CTOs in leg arteries arecomposed of smooth muscle cells, connective tissue, calcium, thrombus,lipids and inflammatory cells. These lesions may be more than 20 cm inlength. Often they are heavily calcified or fibrotic.

FIG. 2 shows arteries of the human leg, as follows:

EI External Iliac Artery DF Deep Femoral Artery CF Circumflex Artery SFSuperficial Femoral Artery PO Popliteal Artery TPT Tibioperoneal TrunkAT Anterior Tibial Artery PT Posterior Tibial Artery P Peroneal ArteryThe superficial femoral artery (SF) is a long artery runningsubstantially the length of the thigh. CTOs of the SFA present in up to50% of the patients treated for PAD. As can be seen from FIG. 2, a CTOof the SF can cause diminished blood flow in numerous other downstreamarteries that receive all or part of their arterial blood supply via theSF.

As shown in FIG. 3, the wall of an artery typically consists of threelayers, the tunica intima I (“intima”), tunica media M (“media”) and thetunica adventitia A (adventitia). In some arteries an internal elasticmembrane IEM is disposed between the tunica media M and tunicaadventitia A. The tunica intima I is formed of a relatively thin layerof soft, smooth tissue. On the other hand, the tunica media M is athicker layer which includes elastic fibers and smooth muscle. Thetunica adventitia A comprises connective tissue which acts as aprotective coat around the artery and also helps to attach the artery toadjacent anatomical structures like muscles. When a guidewire becomesentrapped in a subintimal tract within an artery wall, that tract istypically located between the tunica intima I (which is relatively thinand flexible) and the tunica media M (which is thicker and lessflexible).

FIGS. 4A through 4H show an example of a method for bypassing a CTO inan artery using the above-described re-entry catheter device 10 of thepresent invention. The artery has a true lumen TL which is fullyobstructed by an obstruction O (such as a CTO). Initially, as shown inFIG. 4A, a guidewire GW is advanced into the wall of the artery and pastthe obstruction O, thereby creating a subintimal tract SIT locatedsubstantially between the tunica intima and tunica media of that artery.The distal end of the guidewire GW is entrapped within that subintimaltract SIT, as shown.

The proximal end of the guidewire is inserted through guidewire passageaperture 19 and into the guidewire lumen 18 of the re-entry catheterdevice 10 while the balloon 16 is deflated and the device 10 is in itsfirst configuration. As seen in FIG. 4B, the elongate shaft 12 of thedevice 10 is then advanced over the guidewire GW to a position where thedistal portion of the shaft 12 is within the subintimal tract SIT,distal to the obstruction O. Typically, because the subintimal tract SITis a substantially flat passageway between two tissue planes, thenavigation apparatus 14 of the device will typically be oriented suchthat its transverse axis TA is substantially tangential to the truelumen TL of the artery, with the tunica media above the open area 14 cand the tunica intima below the open area 14 c (i.e., referred to belowas the “desired operative orientation.

As shown in FIG. 4C, the guidewire GW is then retracted so that it isentirely within the lumen 18 of the re-entry catheter device 10 and theballoon 16 is inflated, causing the device 10 to transition to itssecond configuration. Because the tunica intima presents less resistancethan the tunica media, the expanding balloon 16 will bulge below thenavigation member 14 in the direction of the true lumen TL and thenavigation member will be pressed against the relatively rigid tunicamedia. This causes the distal portion of the shaft 12 to also curvedownwardly such that its distal end DE is directed toward the true lumenTL of the artery.

As shown in FIG. 4D, the guidewire is then advanced out of the opendistal end DE of the re-entry catheter device 10, through theintervening tissue of the tunica intima and into the true lumen TL,distal to the obstruction O. The angle at which the guidewire GWadvances may be sufficiently oblique to prevent the distal tip of theguidewire GW from directly impinging against the opposite side of theartery wall.

Thereafter, the balloon 16 is deflated causing the device 10 to returnto its first configuration. The device 10 is then removed, leaving theguidewire GW in place as shown in FIG. 4E.

Thereafter, as seen in FIG. 4F, one or more working devices (e.g.,balloon catheters, atherectomy catheters, stent delivery catheters,laser catheters, etc.) may then be advanced over the guidewire GW andused to enlarge (e.g., dilate, debulk, bore, stent, etc.) the subintimaltract SIT. In this particular non-limiting example, the workingdevice(s) comprises a balloon catheter 30 having a stent 32 mountedthereon. The balloon catheter 30 is advanced over the guidewire GW to aposition where one end of the stent 32 is in the true lumen TL proximalto the obstruction O and the other end of the stent 32 is in the truelumen TL distal to the obstruction O. The balloon of the ballooncatheter 30 is then inflated to dilate the subintimal tract SIT andexpand the stent 32.

Thereafter, as seen in FIG. 4G, the balloon of balloon catheter 30 isdeflated and the balloon catheter 30 is removed, leaving the stent 32 inan expanded configuration and creating a stented, subintimal blood flowchannel around the obstruction O.

FIGS. 5 and 5A show another embodiment of a re-entry catheter device 10a. In this embodiment, the device 10 a has not one but two navigationapparatuses 40 a, 40 b attached to the elongate shaft 12 a. The firstnavigation apparatus 40 a is on one side of the balloon 16 a and thesecond navigation apparatus 40 b is on an opposite side of the balloon16 a. In this non-limiting example, each navigation apparatuses 40 a, 40b comprises a loop-like structure that has a proximal portion that iswider than its distal portion. The balloon 16 a is shown as a generallycircular balloon that is positioned between the relatively narrow distalportions of the navigation apparatuses 40 a, 40 b. As the ballooninflates, its width exceeds the widths of the open areas within theadjacent distal portions of the navigation apparatuses 40 a, 40 b. Thus,the inflated balloon 16 a remains between the navigation apparatuses 40a, 40 b and one of the navigation apparatuses 40 a, 40 b is forced topivot away from the longitudinal axis of the catheter shaft 12 a. If onenavigation apparatus 40 a or 40 b is positioned against tissue thatpresents more resistance to outward displacement of that navigationapparatus 40 a or 40 b than does tissue located adjacent to the othernavigation apparatus 40 a or 40 b, whichever navigation apparatus 40 aor 40 b is presented with the least resistance will tend to pivotoutwardly to a greater degree than the other navigation apparatus 40 aor 40 b. This is illustrated specifically in the methodological exampleshown in FIG. 6.

With reference to FIG. 6, this embodiment of the re-entry catheterdevice 10 a may be advanced over a subintimally entrapped guidewire GWin the same manner as described above with respect to the firstembodiment of the device 10. After the re-entry catheter device 10 a hasbeen advanced to a position within the subintimal space distal to thearterial obstruction O, the guidewire GW is retracted fully into thecatheter shaft 12 a. The first navigation apparatus 40 a is injuxtaposition to the tunica media TM of the artery wall which, asexplained above, is backed up by the tissues of the tunica adventitiaTA. The second navigation apparatus 40 b is juxtapositioned with theadjacent tunica intima TI which divides the subintimal tract from thetrue lumen TL of the artery. The tunica media TM and surrounding tunicaadventitia TA present substantial resistance to pivotal movement of thefirst navigation member 40 a in the outward direction (away from thetrue lumen TL) while the relatively thin tunica intima TI presents onlyslight resistance to pivotal movement of the second navigation member 40b in the inward direction (toward the true lumen TL). Thus, as seen inFIG. 6, when the balloon 16 a is inflated, the first navigationapparatus 40 a lies firmly against the adjacent artery wall with littleor no outward pivotal movement while the second navigation apparatus 40b is forced, by the expanding balloon 16 a, to pivot inwardly causingthe tunica intima TI to bulge into the true lumen TL and causing thedistal portion of the catheter shaft 12 a to curve accordingly. Thiscauses the opening in the distal end DE of the catheter shaft 12 a to bedirected toward the true lumen TL of the artery. The guidewire GW isthen advanced out of the distal end opening of the catheter shaft 12 a,through the intervening tissue of the tunica intima TI and into the truelumen TL at a location distal to the obstruction O.

The devices 10, 10 a of the present invention may be constructed of anysuitable materials in any suitable ways. In the examples shown, thenavigation apparatuses 14, 40 a/40 b may be formed from wire (e.g.,nickel titanium wire) having a round or substantially round crosssection and may be attached to the catheter shaft 12 by any suitablemeans such as, for example, crimping, frictional engagement,overwrapping, shrink-wrapping, thermal welding, resin welding, adhesive,interlocking with depressions or other surface features formed on thecatheter shaft 12, etc. As an alternative to wire construction, thesenavigation apparatuses 14, 40 a/40 b may be formed from other elongatesegments of material (e.g., strips or ribbons) or may be cut (e.g.,laser cut) from a tube or other work piece. FIGS. 7 through 8B show somenon-limiting examples of stent-like navigation apparatuses of presentinvention which are cut (e.g., laser cut) from a nickel-titanium tubingusing equipment and procedures which have become well established in themanufacture of stents.

FIGS. 7 through 7D show a stent-like navigation apparatus component 100that incorporates a single navigation apparatus 14 having a firstnavigation member 14 a, a second navigation member 14 b, an open area 14c and a distal end having a guidewire aperture 19, as generally shown inFIGS. 1-1D. However, in this device embodiment, rather than being formedby shaping of wire or other elongate member(s), the entire navigationapparatus component 100 comprises a unitary one-piece structure that hasbeen laser cut from a nickel-titanium tube. This embodiment of thenavigation apparatus component 100 may be successively pre-formed bymeans of a thermal treatment to provide the desired expanded/enlargedstate (seen in FIGS. 7A, 7C and 7D) to better guide the device into thesubintimal tract. As shown, this navigation apparatus component 100includes three generally cylindrical stent-like regions 102, 104 and106. In the non-limiting example shown, the proximal and distalstent-like regions 102, 106 comprises single zig zag rings while themiddle stent like region 104 comprises two zig zag rings with aperforated area between them. The non-zig-zaged tube portion betweenregions 102 and 104 functions as a hinge to facilitate deployment of thefirst and second navigation members 14 a, 14 b in the desired bowedconfigurations as seen in FIGS. 7A, 7C and 7D. As an alternative to thezig zag design of the stent-like regions shown in this example, it is tobe appreciated that various other designs (e.g., lattice, mesh,perforations, etc.) may be used. The proximal and middle stent-likeregions 102, 104 are initially expanded to a diameter that allows themto be positioned over the distal portion of the catheter shaft 12 to aposition where the deflated balloon 16 and distal end of the cathetershaft 12 extend into the open area 14 c, with the distal end of thecatheter shaft 12 being slightly proximal to the distal stent-likeregion 106. Thereafter, the proximal stent-like region 102 and theproximal portion of the middle stent-like region 104 are radiallycontracted or crimpled tightly around the catheter shaft 12 so that theyfirmly grasp and frictionally engage the catheter shaft. Depressions(e.g., grooves) may be formed in the catheter shaft 12 and an adhesivemay be applied to further bond these areas to the catheter shaft 12.When the first and second navigation members 14 a, 14 b are expandedoutwardly to the bowed configurations shown in FIGS. 7A, 7C and 7D,widened areas 108 of the navigation members 14 a, 14 b are preferablyprovided. In fact, as the balloon 16 inflates, the widest region of theballoon 16 contacts these widened areas 108 of the first and secondnavigation members 14 a, 14 b. The widened areas 108 serve to distributeforce over a greater area of the balloon wall thereby facilitating thedesired protrusion of the expanding balloon 16 to one side of thenavigation apparatus 14 and lessening the potential for damage to theballoon 16 as it inflates. Alternatively, the widened regions 108 can beprovided along the whole axial extension of the navigation membersbetween middle and distal stent-like regions.

FIGS. 8 through 8B show another stent-like navigation apparatuscomponent 140. In this embodiment, the stent-like navigation apparatuscomponent 140 incorporates dual navigation apparatuses 40 a, 40 b whichfunction generally in the manner described above with respect to FIGS.5-6. However, in this stent-like embodiment, the navigation apparatuscomponent 140 comprises a unitary one-piece structure that has beenlaser cut from a nickel-titanium tube rather than being formed from wireor other elongate member(s). This embodiment of the navigation apparatuscomponent 140 may be successively pre-formed by means of a thermaltreatment to provide the desired expanded/enlarged state (seen in FIGS.8A and 8B) to better guide the device into the subintimal tract. Asshown, this navigation apparatus component 140 includes a proximalcatheter mounting portion having two generally cylindrical proximal anddistal stent-like regions 142 and 144 with the two navigationapparatuses 40 a, 40 b extending distally from the distal stent-likeregion 144. In the non-limiting example shown, the proximal stent-likeregion 142 comprises a single zig zag ring and the distal stent-likeregion 144 comprises two zig zag rings with a perforated area betweenthem. This perforated area functions as a hinge to facilitate pivotalmovement of the upper and lower navigation apparatuses 40 a, 40 b. Theproximal and distal stent-like regions 142, 144 are initially expandedto a diameter that allows them to be positioned over the distal portionof the catheter shaft 12 to a position where the deflated balloon 16 isbetween the upper navigation apparatus 40 a and the lower navigationapparatus 40 b. Thereafter, the proximal stent-like region 142 and theproximal zig zag portion of the distal stent-like region 144 areradially contracted or crimpled tightly around the catheter shaft 12 sothat they firmly grasp and frictionally engage the catheter shaft.Depressions (e.g., grooves) may be formed in the catheter shaft 12 andan adhesive may be applied to further bond these areas to the cathetershaft 12. Each navigation apparatus 40 a, 40 b comprises a loopstructure when in its final expanded state, as seen in the views ofFIGS. 8A and 8B. These navigation apparatuses 40 a, 40 b are initiallypositioned in substantial parallel over and under the deflated balloon16 so that, as the device is advanced within the subintimal tract, theupper and lower navigation apparatuses 40 a, 40 b will direct and orientthe device to follow the natural curvature of the vessel wall. When thedevice has been advanced past the obstruction, the balloon 16 isexpanded causing the upper navigation apparatus 40 a to be maintained insubstantial contact with the outer (media/adventitia) aspect of thevessel wall while the other navigation apparatus 40 b pivots inwardlytoward the vessel true lumen thereby causing the intima to buldge intothe true lumen and directing the distal end of the catheter toward thetrue lumen in the same manner as shown in FIG. 6. Since the resistanceoffered by the media/adventitia is greater than that offered by theintima, whichever navigation apparatus which is closest to themedia/adventitia (e.g., upper navigation apparatus 40 a in the exampleof FIG. 6) will be maintained in its original position while the othernavigation apparatus (e.g., lower navigation apparatus 40 b in theexample of FIG. 6) move (e.g., bend or pivot at the hinged area of thedistal stent-like region 144) towards the intima and thus towards thetrue lumen for re-entry into the true lumen. It is to be noted, withreference to the showing of FIG. 6, that in embodiments having the dualnavigation apparatuses 40 a, 40 b, expansion of the balloon is preventedin the direction where the media/adventitia and adjacent navigationapparatus are present, therefore the balloon can expand in the directionof the intima/true lumen and thus it orients the catheter tip in thatdirection. In this embodiment, the balloon 16 is not constrained withinthe navigation apparatus. Therefore, the balloon expansion will notoccur only in the direction where the media/adventitia is present, butit will cause navigation apparatus adjacent to the intima to move (e.g.,bend or pivot) towards the intima/true lumen.

Optionally, an outer sheath could be present around the navigationapparatuses 40 a, 40 b during insertion and advancement of the devicethrough the subintimal tract. When the device has reached its operativeposition distal to the obstruction, such sheath could be retractedthereby releasing the upper and lower navigation apparatuses andallowing the balloon 16 to be expanded. The sheath (if present) isretracted immediately after_the catheter is inserted in the subintima.In this way, the navigation of the catheter within the vessel isprotected by the sheath and also access to the subintimal space occurswith the sheath over the navigation apparatus, thereby avoiding any riskthat the navigation apparatus may cause any damage to the vessel wall.When the sheath is removed, the navigation apparatus 14 can be used forsuitably navigating the device along the subintimal space. The inclusionof an outer sheath may be of heightened utility in embodiments havingtwo navigation apparatuses 40 a, 40 b (e.g., see FIG. 5), but may alsobe useful in the other embodiments of the invention as well.

The configuration wherein the expandable member is non-expanded(indicated above as the first configuration) is typical of at least twodistinct operating conditions of the guidewire directing device of thepresent invention. In fact, it is possible to identify a first conditionin which the device navigates within the true lumen of the blood vesselto be treated and the navigation apparatus is substantially straight andfollows the blood vessel path, and a second condition in which thedevice enters the subintimal space and the navigation apparatus—still inthe straight configuration—is suitably used for creating a path in thesubintimal space and providing a proper orientation (i.e. with thenavigation apparatus or the navigation members thereof substantiallyparallel to the vessel wall) and a suitable stability to the device. Incase a sheath is used, the sheath is positioned over and around theguidewire directing device when the latter is in the first conditionmentioned above, while the sheath is retracted and the navigationapparatus exposed when the device is in the second condition.

It is to be appreciated that, although the examples shown in thedrawings and described above utilize an inflatable balloon 16, variousother expandable members could be used instead of a balloon. Forexample, the distal portion of the catheter shaft 12 could be formed oftwo pieces or could be otherwise designed to be alternately lengthenedand foreshortened and an expandable structure such as a mesh cage or thelike could be mounted thereon such that, when the distal portion of thecatheter shaft is foreshortened, the expandable member will shorten andradially expand, and when the distal portion of the catheter shaft isreturned to its non-foreshortened state, the expandable member willagain lengthen and radially contract.

It is to be further appreciated that the guidewire re-entry proceduresof the present invention may, in at least some cases, be accomplishedusing a single guidewire (e.g., a 0.035 inch guidewire). The guidewirethat is initially used to create the subintimal tract SIT may be causedto re-enter the true lumen of the artery and then may serve as theguidewire for subsequent ballooning and stenting of the subintimaltract. The ability of the present invention to complete the entireendovascular bypass procedure using a single guidewire, without the needfor guidewire exchanges or re-selection of the subintimal tract, mayresult in savings of both time and money when compared to otherguidewire re-entry procedures wherein guidewire exchanges and aplurality of guidewires of different sizes are required.

Additionally, it is to be appreciated that, although the invention hasbeen described hereabove with reference to certain examples orembodiments of the invention, various additions, deletions, alterationsand modifications may be made to those described examples andembodiments without departing from the intended spirit and scope of theinvention. For example, any elements, steps, members, components,compositions, reactants, parts or portions of one embodiment or examplemay be incorporated into or used with another embodiment or example,unless otherwise specified or unless doing so would render thatembodiment or example unsuitable for its intended use. Also, where thesteps of a method or process have been described or listed in aparticular order, the order of such steps may be changed unlessotherwise specified or unless doing so would render the method orprocess unsuitable for its intended purpose. Additionally, the elements,steps, members, components, compositions, reactants, parts or portionsof any invention or example described herein may optionally exist or beutilized in the substantial absence of other elements, steps, members,components, compositions, reactants, parts or portions unless otherwisenoted. All reasonable additions, deletions, modifications andalterations are to be considered equivalents of the described examplesand embodiments and are to be included within the scope of the followingclaims.

What is claimed is:
 1. A guidewire directing device comprising: anelongate shaft having a distal portion with a distal end and a lumenthat extends to a distal outlet opening; an expandable member on thedistal portion of the elongate shaft; a first navigation apparatuspositioned on one side of the expandable member; and a second navigationapparatus positioned on an opposite side of the expandable member,proximal ends of the first and second navigation apparatuses beingconnected to the elongate shaft and distal ends of the first and secondnavigation apparatuses being unconnected to the elongate shaft andseparate from each other, and the guidewire directing device beingtransitionable between: a) a first configuration wherein the expandablemember is non-expanded and the distal portion of the elongate shaft issubstantially straight; and b) a second configuration wherein theexpandable member is expanded, thereby causing whichever navigationapparatus encounters the least resistance to diverge laterally more thanthe other navigation apparatus, thereby resulting in curvature of thedistal portion of the elongate shaft in the direction of leastresistance.
 2. A device according to claim 1 wherein the elongate shaftcomprises a catheter.
 3. A device according to claim 1 wherein the firstand second navigation apparatuses each comprises a loop-like structure.4. A device according to claim 3 wherein the loop-like structure definesan open area, each loop-like structure including a proximal portion anda distal portion, the expandable member being positioned between thedistal portions of the first and second navigation apparatuses; and whenthe expandable member is expanded to an expanded configuration, a widthof the expandable member exceeds a width of the open areas within thedistal portions of the first and second navigation apparatuses, therebycausing the expandable member to displace to whichever of the first andsecond navigation apparatuses presents the least resistance to itsexpansion and causing curvature of the distal portion of the elongateshaft toward that navigation apparatus.
 5. A device according to claim 3wherein the loop-like structure includes a proximal portion and a distalportion, the proximal portion being wider than the distal portion.
 6. Adevice according to claim 1 wherein the expandable member comprises aballoon.
 7. A device according to claim 6 wherein the balloon iscompliant.
 8. A device according to claim 6 wherein the balloon isconfigured in a shape that facilitates displacement of the balloon, wheninflated, to one side of a longitudinal axis of the elongate shaft.
 9. Adevice according to claim 1 wherein the expandable member comprises anexpandable cage structure.
 10. A device according to claim 9 wherein theexpandable cage structure is configured to a) foreshorten with resultantwidening of the cage structure when the device is transitioned from thefirst configuration to the second configuration and b) lengthen withresultant narrowing of the cage structure when the device istransitioned from the second configuration to the first configuration.11. A device according to claim 1 wherein the first and secondnavigation apparatuses comprise loop-like structures.
 12. A deviceaccording to claim 11 wherein each of the loop-like structures has adistal portion defining an open area adjacent to the expandable memberand, when expanded, the expandable member is too wide to pass throughthe open area.
 13. A device according to claim 1 further comprising anavigation apparatus component that is cut from a tube, wherein thenavigation apparatus component includes the first and second navigationapparatuses.
 14. A device according to claim 13 wherein the tubecomprises a nickel titanium alloy tube.
 15. A device according to claim13 wherein the navigation apparatus component is laser cut from thetube.
 16. A device according to claim 13 wherein the navigationapparatus component comprises one or more stent-like regions that aremounted on the elongate shaft, the first and second navigationapparatuses extending distally from at least one of the stent-likeregions.
 17. A device according to claim 16 wherein one or moredepressions are formed in the elongate shaft and the one or morestent-like regions of the navigation apparatus component are seatedwithin the one or more depressions.
 18. A device according to claim 1wherein the first and second navigation apparatuses each comprises aloop-like structure including a proximal portion and a distal portion,wherein when the device is in the first configuration, the expandablemember is positioned between the distal portions of the first and secondnavigation apparatuses.
 19. A device according to claim 18 wherein theloop-like structure defines an open area, and wherein the expandablemember has a width, when in the second configuration, that is greaterthan the widths of the open areas within the distal portions of thefirst and second navigation apparatuses so that expansion of theexpandable member causes the expandable member to displace laterally towhichever side of the device includes the navigation apparatus thatpresents the least resistance to its expansion.